Here are short profiles of the two negotiators:

- Witkoff: real estate to world stage -

With no prior experience in foreign policy, he landed one of the world's biggest jobs as US President Donald Trump's special envoy to the Middle East, and has since led high-stakes talks on Gaza and Ukraine.

Real estate magnate Steve Witkoff first stepped into the spotlight when his close friend Trump credited him with sealing a truce in the Israel-Hamas war.

While the ceasefire collapsed weeks later, it did enable the release of 25 living hostages and the return of eight others' remains.

Witkoff, a 68-year-old billionaire and a regular golfing partner of Trump's, later became the first US official to visit Gaza since the war began with Hamas's 2023 attack on Israel.

He defended Trump's stunning suggestion that he wanted to "take over" the Palestinian territory and move out its two million inhabitants.

"When the president talks about cleaning it out, he talks about making it habitable, and this is a long-range plan," Witkoff told reporters at the White House.

Witkoff has also spearheaded negotiations on Ukraine, with Trump U-turning on his predecessor Joe Biden's policy on Russia.

He was in Russia to meet Russian President Vladimir Putin when a scandal erupted over a leaked Yemen air strike chat on the Signal app that involved National Security Advisor Mike Waltz and other officials.

Witkoff himself has drawn criticism from Ukraine's leader Volodymyr Zelensky over his praise for Putin and for appearing to legitimise Russia's annexation of parts of Ukraine.

In March, he was Trump's man in Saudi Arabia for talks on Ukraine, voicing optimism that any agreement struck could pave the way for a "full-on" ceasefire.

Trump has made it a foreign policy goal to end wars that Biden could not stop, meaning that the stakes could hardly be higher for Witkoff.

Ultimately, Witkoff's win in Gaza was short-lived, with US ally Israel restarting intense strikes on March 18.

On Ukraine, the Russian president has yet to accept a long-term truce.

Born on March 15, 1957, in the New York borough of the Bronx, Witkoff made his fortune in real estate, first as a corporate lawyer and then at the head of big realty firms.

In 1997, he founded the Witkoff Group, which describes itself as "one part developer, one part investor (and) one part landscape-changer." His wife and a son work there.

- Araghchi: Iran's career diplomat -

A career diplomat and key architect of the 2015 nuclear accord, Araghchi will be pushing the United States to lift its punishing sanctions on Iran.

The 62-year-old, who hails from a family of carpet traders, is fluent in English and has a long career spanning multiple roles in Iran's foreign ministry.

With his crisp beard and salt-and-pepper hair, Araghchi is known for his calm demeanour. He typically wears a suit and a tie-less white mandarin-collared shirt, a standard look among Iranian diplomats.

He holds a bachelor's degree from the foreign ministry's Faculty of International Relations, a master's in political science from the Islamic Azad University, and a doctorate in political thought from the University of Kent in England.

Following the 1979 Islamic revolution, Araghchi joined the Islamic Revolutionary Guard Corps.

He served on the front lines during the Iran-Iraq war in the 1980s before joining the foreign ministry as an expert on international affairs.

Araghchi was appointed foreign minister after President Masoud Pezeshkian, who has called for reviving talks with the West, took office in July.

He was the chief negotiator at the talks that culminated in the 2015 landmark nuclear deal with world powers, which imposed curbs on Iran's nuclear programme in return for sanctions relief.

The Joint Comprehensive Plan of Action (JCPOA) fell apart after the United States, during Donald Trump's first term, unilaterally withdrew from it and reimposed sweeping economic sanctions.

Araghchi remains a fervent supporter of the deal but said in a recent interview with Khabar Online news agency that the JCPOA "cannot be revived in its current form and text."

"Our nuclear programme has advanced significantly and we can no longer return to the conditions of the JCPOA," he said, adding that the deal "can still be a basis and a model for negotiations".

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